Carburetor



Sept. 18, 1934. w. A. DOBLE, JR 51 CARBURETOR Filed Nov. 26, 1928 2 Sheets-Sheet 1 A TTOR E YS Se t.- 18, 1934. w. DOBLE, JR 1,973,751

I CARBURETOR Filed Nov; as, 1928 2 Shets-Sheet 2 INVENTOR 1407/40/77 4. flab/z J/r Mai w ATTORNEYS Patented Sept. '18, 1934 UNITED STATES PATENT OFFICE i OARBURETOR William A. Doble, Jr., Berkeley, Calif. Application November 26,1928, Serial No. 321,891

2.Claims.. (cl. 261-29) My invention relates to means for supplying fuel to internal combustion engines and is especially applicable to such engines operating on the so-called Otto or Beau de Rochas cycle.

It is an object of my invention to provide an internal combustion engine operating on moderate compression pressures and utilizing relatively heavy fuel oil.

Another object of my invention is to provide a suitable means for supplying heavy fuel oil to the intake manifold of an Otto cycle engine.

Another object of my invention is to provide a means for handling heavy fuel oil so that it can be aspirated from a nozzle in the manner of the 16 customary gasoline carburetor.

An additional object of my invention is to provide an engine having substantially all of the characteristics of the customary gasoline operated Otto engine but which is capable of operating on relatively heavy fuel oil.

The foregoing and other objects are attained in the embodiment of the invention shown in the drawings, in which Fig. 1 is a side elevation of a conventional engine provided with the apparatus of my invention.

Fig. 2 is a cross section on a vertical plane of the carburating portion of my apparatus.

Fig. 3 is a cross section on the line 3-3 of Figure 1 disclosing the interior of the foam pump.

In its preferred form, the internal combustion engine of my invention is provided with an air intake manifold operated in conjunction with a means for supplying to the manifold a combustible proportion of a fuel foam which includes heavy fuel oil and air. 7

While the device of my invention is susceptible to numerous variations and adaptations to different environments, it is conveniently applied to a conventional multi-cylinder internal combustion engine 6 of the type operating according to the Ottocycle and employing moderate compression pressures and electric spark ignition. This engine is provided with the usual intake manifold '7 leading to the combustion chambers. Secured to the'entrance of the intake manifold 7 is a body 8 having an air passage 9 extending therethru and terminating in an air horn 11. A suitable butterfly valve 12 regulates the influx of air to the body 8 while a second butterfly valve 13 regulates the efllux of air therefrom.

In accordance with my invention, I preferably mix a fuel foam composed largely of heavy fuel oil and air with the air flowing through passage 5 9 and I therefore provide means for handling such fuel foam. Mounted on-the body 8 is a housing 14 having a connection 16 leading to a fuel supply device 18 of any desired type. This device withdraws fuel through a conduit 19 from a source of supply, not shown, and delivers it into the housing 14. I deem it advisable to maintain a substantially constant, pro-determined level of liquid fuel in the chamber 14 and one means of effecting this result'is shown in Figure 2. Projecting into the 05 .housing 14 is a stand pipe 21 terminating at the predetermined height and leading through a conduit 22 back to the supply tank. Liquidfuel is introduced by the device 18 through the conduit 16 into the housing 14 and any surplus over- Hows the stand pipe 21 and returnsto the supply. tank.

For providing the fuel foam, I preferably install a so-cal1edfoam.' pump 23 at any convenient point of the engine andfas shown in Figure 1, the pump is expediently driven by a chain 24 connected to the crank shaft 26 of the engine. This form of pump drive is preferred, although numerous other forms can be used successfully. The pump itself includes a casing 27.80 having a central cylindrical bore in which an ce- I centric rotor 28 revolves. The rotor is provided with projecting vanes 29 contacting the interior surface of the casing 2'7 and affording a positive pump to propel material entering through the inlet 31 toward the outlet 32.

Connected to the inlet is a conduit 33 which extends in two branches 34 and 36 to the housing 14. The lowermost branch 34 is below the predetermined liquid level in the housing and provides a passage for the heavy fuel oil contained therein. The upper branch 36 enters the housing 14 above the predetermined liquid level and withdraws from the interior of the housing air which has been admitted thereto through a port 35 leading to the air horn 11.

At the confluence of the branches 34 and 36' the air and oil are mixed together and flow through the conduit 33 to inlet 31 of the pump. The rapid revolution of the rotor 28 when the efigineis operating serves to whip and churn the v entering mixture of air and fuel into a homogeneous light fuel foam. The specific gravity of the fuel foam is lowered from the specific gravity of the oil alone to a value approximating the specific gravity of gasoline. This light foam is discharged by the fuel foam pump through the outlet 32 into a conduit 3'1 leading back to the housing 14 and promcting thereinto asufficient distance to deliver the foam into arecepfacle 38.

This receptacle is preferably cup shape and is situated with its upper lip 39 a suflicient distance below the bottom of the body 8 to permit the overflow of any surplus foam supplied thereto. The lower end of the receptacle is provided with a depending tube 41 so that any fuel oil which separates from the foam is returned through the tube 41 to the main body of fuel in the casing 14.

Inasmuch as the fuel foam contained in the receptacle 38 is of a relatively low specific gravity it can be readily aspirated under the influence of the air current flowing through the passage 9 during the operation of the engine. To effect this result I dispose a nozzle 42 in the lower wall of the body 8 and terminate its lower end well within the receptacle 38'. The upper end is in close proximity to a venturi 43 provided in the passage 9 so that the velocity of air flowing through the venturi is ample to aspirate the fuel foam through nozzle 42 from the receptacle 38.

Preferably the parts are so proportioned that the rate of eiilux of the fuel foam through the nozzle 42 is substantially the same as the rate of influx of fuel foam through the conduit 37' leading from the pump. But in case of an excess supply of fuel foam, the additional amount overflows the upper lip 39 of the receptacle and -deposits on the surface of the fuel at the predetermined level. If this excessquantity becomes sufficient it is drawn through the air conduit 36 and is recirculated.

The pressure existing within the passage 9 varies largely in accordance with the position of the butterfly valve 12, and the amount of fuel foam aspirated is correspondinglyin the proper, defl nite proportion. In starting there is sometimes required an extra rich mixture or one which has a great proportion of fuel foam to air. In this event, closure of the-butterfly valve 12 reduces the air pressure in the passage 9, precludes the entrance into the housing 1.4 of the normal quantity of air and insures the aspiration of a greater proportion of fuel foam through the nozzle 42. It

may occasionally happen that the velocity of flow through the passage 9 is too low to provide a suitable mixture for. engine operation at low speed and I therefore provide an idling aperture 44 piercing the side of the body 8 and communicating with passage 9 at a point near the edge of the butterfly valve 13 in closed position. The size of the aperture 44 is adjustable by a thumb screw to the form of the internal combustion engine shown and described herein, as the invention, as set forth in the following claims may be embodied in a plurality of forms.

I claim:

1. An internal combustion engine including an air intake manifold, a housing mounted on said manifold, means for maintaining a predetermined level of liquid fuel in said housing, a fuel foam pump, means for conducting fuel from said housing to said pump, means for conducting air from above said predetermined level in said housing to said pump, a receptacle in said housing above said predetermined level, means for conducting fuel foam from said pump into said receptacle, and means for conducting fuel foam from said receptacle into said manifold.

2. A fuel system for an internal combustion engine including, an induction pipe, a housing mounted thereon and in communication therewith, means for maintaining a predetermined level of liquid fuel in said housing, a fuel foam receptacle mounted in said housing above said fuel level, a fuel foam generator operable for gen-. erating a foam of fuel and air, means for conducting fuel from said housing to said generator, means for conducting air from said housing from above said predetermined fuel level to said generator, means for conducting fuel foam from said generator into said receptacle, and an aspirating means operable by the air stream flowing through said induction pipe for aspirating said foam from said receptacle into said air stream.

WILLIAM A. DOBLE, Ja. 

